Koteiv (Writing) - Breaking Down the 39 Melachot

You want to take a walk on Shabbat afternoon,  but the ground is very muddy. Are you allowed   to walk in the muddy area if you know  your steps will create footprints or   even sometimes write the brand of the shoe  into the mud? One of the melachot of Shabbat   is the melacha of Koteiv, which means writing  or creating a meaningful picture. Generally,   you're not allowed to create any kind of  lettering or picture. However, in this case,   since it's not your intention to create the  footprint, it's a strange way to create a picture,   and lastly, generally it won't last, in this case,  it is allowed to walk through the muddy area.